This invention generally relates to a system for and method of recording and retrieving a machine readable image on unprocessed motion picture film stock. In a particular embodiment, this invention specifically relates to motion picture and television film production systems where the machine readable image contains specific film footage and frame identification information pertinent to the latent image on the film.
In motion picture feature and television production, many stages of the photographic imaging process are necessary to progress from the image capture stage until the final edited product is ready for distribution. In order to better explain modem editing processes, it is important to understand how film is manufactured and some basic procedures required in the actual production or shooting phase. Motion picture film is manufactured by coating a transparent support material with light sensitive emulsion layer(s), and an opaque antihalation layer coated either as a dyed layer between the light sensitive emulsion and the support or a pigmented or dyed layer on the side of the support opposite to the light sensitive emulsion. Many camera origination films employ a carbon black containing backing xe2x80x9cremjetxe2x80x9d layer as the antihalation layer. There are perforated sprocket holes at the edges of the film to allow for sprocket drives to pull the film through the motion picture cameras, printers, editing machines and projectors. Depending on the type of emulsion used, a positive or negative image (in color or black and white) will be produced on the film when it is properly exposed in the camera and subsequently processed at the film laboratory, wherein the antihalation layer is either removed (in the case of carbon black containing backing layers) or the dyes thereof rendered substantially colorless. Most all professional film production uses negative type film.
Once the original camera negative film is processed, the laboratory will then make a positive print of this film so that it may be viewed and edited. This print may be variously called the work print, direct print, or answer print. Upon completion of the editing process, the edited workprint is sent to a film cutter who will take the original camera negative or a print from the negative and cut it up to match the edited workprint. Positive prints, called release prints, can then be generated from this cut film and used for projection and/or transferred to videotape for showing on TV.
A key point in the editing process is the generation of an edit decision list (EDL) which provides specific negative film product and emulsion codes, footage and frame count information to the negative cutter to conform the negative images in the sequences desired for the end product. Because of the desire to maintain handling of the film at a minimum, and the importance of an exact frame reference as input to the film cutter, it is imperative that the EDL contain accurate references to the image frame identification on the film to be cut. In order for the film to be cut to exactly match up to the edited workprint, the film cutter relies on encoded information written near the edge of the film, such as the Eastman Kodak KEYKODE number. Such encoded information is typically provided by film manufacturers during the manufacturing process in the form of both human readable (e.g., alphanumeric characters) and machine readable (e.g., standard bar-code USS 128) images on the raw stock camera negative as a means of accurate frame identification. Written near the edge of the film, these human- and machine-readable alphanumeric and bar-code systems provide information on film code and emulsion identification, as well as unique film footage and frame counts corresponding to the images on the film. An industry standard for this encoded information system exists and this system is conventionally used in the motion picture production chain.
Currently, encoded information such as KEYKODE numbers are written in the form of latent images by exposing the photosensitive layer(s) of the film stock at regular intervals near the edges of the film during the manufacturing process, outside the intended picture area of the film according to SMPTE (Society of Motion Picture and TV Engineers) standards (e.g., Standard ANSI/SMPTE 271-1994 (16 mm), ANSI/SMPTE 254-1992 (35 mm) and ANSI/SMPTE XXX-YYYY (65 mm)), typically using a laser or light emitting diode (LED) device to form a latent image. Upon photographic processing, the latent images are developed to generate optical human (e.g., alphanumeric) and/or machine (e.g., bar-code) readable dye or silver images. There are specially designed film bar-code readers that the editor and negative cutter can utilize to read KEYKODE numbers. Among other things, the KEYKODE number acts as a roll and frame counter, by which any frame of a production may be absolutely identified. KEYKODES provide information on film code and emulsion identification, as well as unique film footage and frame counts corresponding to the images on the film. The encoded information can then be used in the editing, color timing and telecine transfer processes to identify and select frame positions for splicing, color timing changes such as printer light changes, fades and dissolves, and sound synchronization points in an on-line or off-line film editing system. Importantly, film stock that the film laboratory uses to make the positive workprint does not contain these KEYKODE numbers, rather they are printed through from the processed original camera negative along with the main picture image.
The motion picture film latent image encoded information system is well-known in motion picture processing and provides very valuable information for the editing and color timing processes. This system is useful for providing a frame search, identification and orientation process to make reliable and accurate cuts when performing on-line, off-line telecine edits and final negative cutting edits. Furthermore, with the manufacturer""s ID information incorporated into the encoded information, tracking information is retained in the film should it be necessary in the future.
A simplified representation of a typical process flow diagram for motion picture film production and post production stages is shown in FIG. 1. Camera origination film is exposed in a motion picture camera in Image Capture Stage 10. With the current film system as discussed above, the manufacturer latent image written encoded (human and machine readable) information is neither readable nor usable until the film has been processed in Film Processing step 20. Although a video tap in the camera can provide an image to an on set Video Tap Color Monitor 40 for the cinematographer and director to review, there is no exact footage and frame reference corresponding to this image that was provided from the unprocessed camera negative film. Hence, this monitor image can be used only for general evaluation of a take and not for producing a final or rough EDL of what negative footage is most desirable. Rather, the latent image recorded encoded information is typically transferred from the processed negative film to a work print or intermediate film in a optical Printer 50, or read from the processed negative in a Telecine transfer device 60, and the EDL is then prepared upon review of the work print or telecine transfer at Off-Line Editor stage 70. The EDL is then supplied to Negative Cutter stage 80. This is a major limitation with the current latent image encoded information system. Because the human and machine readable images are not available until after processing, there is no method to accurately begin the editing process by corresponding the images on an on set monitor (via the video tap) to the actual frames for cutting, fading, dissolving etc. Another limitation of this process is in the use of special effects shooting, where it is essential to exactly match specific frames for instance when shooting background and matte exposures.
There exists methods to write an in-camera timecode to provide synchronization between image frames recorded on multiple cameras and/or sound recording devices, such as illustrated in box 30 of FIG. 1. Time-code systems provide some of the information useful to motion picture film post production processes, but not all. Originally developed for the video market, timecode methods have been implemented to allow for simpler post production sound and image synchronization, especially for multi-camera film capture. Conventional systems of this type include both standard timecode systems such as the SMPTE timecode and proprietary systems such as AAtoncode(trademark) (Aaton, Inc., Grenoble, France) and FIS(trademark) (Arri, Munich, Germany). While these systems are not identical, they all operate on the same basic principle, keeping very accurate real or relative time synchronization when using multiple cameras and audio (DAT) and video tape recorders. For film, these systems write a machine-readable code that synchronizes each frame of a motion picture negative with a real or relative time and footage stamp. Some time-code systems also periodically write reference marks and human-readable timecode to the film. This time-code, written as a latent image to the image layers of the film by an LED or similar type of device, becomes a permanent part of the negative film once it is developed. Both the machine and human-readable time-code images can thereby be used in the editing process, making it easier to find, edit and synchronize sound and images recorded from different devices.
Unfortunately there are some inherent limitations with the in-camera written time-code systems. First, there is no robust and accurate reference between the in-camera written time-code and the manufacturer""s optically written latent image encoded information. Hence, the two systems do not allow for easy cross referencing to provide editing information from the timecode display in the video tap or the tape transfer from the telecine to provide exact film frame identification for the images on the negative. This cross-referencing can only be achieved after machine reading the optically recorded information from the processed film on a bar-code reader in a telecine or off-line editor and deriving an EDL from these identifiers. Second, due to the fact that the time-code information is written in-camera, it is subject to variations in exposure conditions of the writing device which can yield unreadable images if not adjusted properly for the correct film speed in the camera, an adjustment that may be needed every time the film stock in the camera is changed. Furthermore, there is much reluctance by personnel in the production process to use this system because of 1) lack of verification that the system is indeed recording to the film properly, 2) lack of understanding of the electronic devices required to synchronize the audio recorders and cameras, 3) unclear definition of who is responsible for the systems operation on the set and 4) general aversion to xe2x80x9canotherxe2x80x9d tool on the set whose benefit appears to be limited to multiple camera and sound synchronization, two quite specific and limited applications.
The use of magnetic recording stripes or layers in photographic elements has been previously disclosed. An innovation in data communication between different stages of film use and processing for motion picture film was introduced as described in the publication xe2x80x9cDATAKODE Magnetic Control Surfacexe2x80x9d by Eastman Kodak Company 1983 (Publication No. V3-517). A layer approximately 5 xcexcm thick containing magnetic oxide particles was coated across the entire back surface of a roll of motion picture film to provide the capability to magnetically record digital data on the film without interfering with normal photographic use of the film. It has been suggested that this permitted recording of different types of digital data at different stages of production of a motion picture which allowed for information exchange such as camera, lighting and filter data at the time of shooting to printer exposure control information in the laboratory to theater automation control signals during exhibition. By incorporating magnetic heads in cameras, processors, telecine apparatus, and other processing equipment, machine readable information can be transferred along with the film. This machine-readable information can include information such as the specific film footage and frame identification information which could be read and encoded in a reader in the camera. The use of magnetic recording strips or layers on motion picture films for recording and playing back audio information has also been disclosed, such as in U.S. Pat. Nos. 4,003,743, 4,279,945, 4,341,855, 5,633,127. More recently, it has been proposed to employ a virtually transparent magnetic layer on still photography filmstrip to allow for magnetic recording of data in one or more longitudinal tracks associated with individual film image frames for information exchange purposes as part of the recently introduced Advanced Photo System. An example of such a system is described in commonly assigned U.S. Pat. No. 4,965,627 issued Oct. 23, 1990. In order to provide quick access to particular data at any stage of film use, related data is preferably grouped and recorded in specific predetermined tracks. Camera data is recorded in several dedicated longitudinal tracks located along the filmstrip edges. The data is preferably recorded in pulse position encoded form in order to be largely independent of film transport velocity. Magnetics On Film (MOF) systems, however, are complex to manufacture and are therefore extremely costly. MOF use requires manufacture of the film support (base) in a manner that is substantially more complex than is used in present manufacturing systems. Additionally, use of MOF technology requires that numerous manufacturers incorporate magnetic read/write heads on various equipment used throughout the production and post production processes.
Laser ablation is used commonly in the sub-titling of motion picture distribution prints, wherein after printing and photographic processing the emulsion layer of a print is selectively ablated (typically with an Argon type laser) to produce different language subtitles. There is no known previous use of ablation marking of light sensitive camera origination films for any purpose.
It would be desirable to provide an improved encoded information marking system which would allow for accurately corresponding the images provided on an on set monitor (e.g., via a camera video tap) to the actual frames of the camera film being exposed so that, e.g., the editing process (e.g., decisions for cutting, fading, dissolving, etc.) may be started based upon the viewed video images, which is currently not possible as readable images provided by the current latent image marking system are not available until after processing. Another limitation of the current system is in the use of special effects shooting, where it is essential to exactly match specific frames for instance when shooting background and matte exposures. A system for and method of recording and retrieving a machine readable image on unprocessed motion picture film stock would also be useful in enabling film in a given camera to be interchanged with another film type and re-threaded to a given spotxe2x80x94for example the position to where the film has been exposed. Such a system may also prevent confusion when different film types are being used in the same camera. Such a system would also be useful to provide specific film information such as exposure characteristics, tone scale, grain, resolution MTF, reciprocity characteristics, halation, latent keeping, and other information. In fact, overall this capability would provide for a more reliable and better controlled photographic and cinematographic capture process.
In accordance with one embodiment of the invention, a camera origination photographic film is described wherein the film comprising pre-processing readable encoded information markings recorded thereon. In accordance with a further embodiment of the invention, a system for encoding motion picture film with information for use in a motion picture camera is described such that the camera can read the encoded information when the film is in the camera, comprising (i) camera origination film having pre-processing readable encoded information markings thereon and (ii) a motion picture camera having an encoded information reader for reading the pre-processing readable encoded information markings. A method for encoding motion picture photographic film with pre-processing machine readable encoded information is also described, comprising physically marking the film with encoded information using laser ablation, inkjet printing, or holographic or binary optic embossing techniques. In preferred embodiments of the invention, the pre-processing readable encoded information markings comprise bar-code markings on the film which may be read with a bar-code reader. In accordance with a further embodiment of the invention, a method for recording synchronized pre-processing readable marks and latent image marks in a photographic film which comprises a transparent support, an emulsion layer coated on one side of the support, and an opaque backing layer on the opposite side of the support is also described, the method comprising (i) laser ablation marking the backing layer to form a pre-processing readable mark, and (ii) exposing the emulsion layer through the transparent support using the ablation marking of the backing layer as a mask to form a latent image in the emulsion layer which corresponds to the ablation marking in the backing layer, which latent image becomes readable after photographic processing.